Au jus is a French term that, although it sounds fancy on a menu, refers to nothing more than meat served in its natural juices. The word jus, pronounced zhoo, refers to the thickened juices from a roast or other meat. Most of us are most familiar with the term being used with prime rib, in prime rib au jus. The term translates literally to “with the juice.” When used in the name of dishes or on restaurant menus, the words au justraditionally appear just after the particular meat it is modifying. However, it has been corrupted in recent times so that au jus is used as a noun, as if it is a particular sauce. For example, we sometimes hear usages such as steak with au jus. This makes no literal sense. Modern cookbooks often tell you how to “make the au jus,” as well.
The correct pronunciation of au jus is something like oh-zhoo but English speakers tend to say oh-zhoos or oh-joos. It should be pronounced without the S and used alone as a modifier. Prime rib au jus means prime rib with the juice. Prime rib with au jus or prime rib with au jus sauce (gravy, broth, etc.) is redundant.
Another confusing misuse of the term is French dip au jus or French dip with au jus. We can already see that “with au jus” is redundant, but, as well, a “French dip” without jus would be nothing more than a dry piece of meat inside bread or a roll. It is meant to be dipped into pan juices. That a French dip is served au jus, therefore, is understood. Roast beef sandwich au jus, which is essentially the same thing, makes more literal sense, and simply mean a roast beef sandwhich served with the jus for dipping.
Although broth is sometimes added to the drippings from a roast in order to extend it, it is not really the same as a gravy, which is the thickened drippings from a meat preparation. However, since when cooking even a large piece of meat, the drippings tend to evaporate and brown in the pan, deglazing the pan with stock or other liquid is customary, and the resultant jus may be seasoned, slightly reduced, and strained. It is not really thickened like a gravy, but the jus, when reduced and strained in this way, is often called a gravy.
Sometimes the word jus is also used to refer to an unthickened liquid flavored with the essence of a certain ingredient, such as a vegetable or mushroom. For example, a mushroom jus can be made by simmering mushrooms in stock or broth until the liquid has a strong mushroom flavor and becomes concentrated. This can then be strained (or passed through a food mill) and used as the basis of a sauce, gravy, soup, etc. A jus made in this way may also be called an essence.
Roast beef au jus image © MSPhotographic